You might want to think twice about raking your leaves this fall, Maryland experts say. Here’s why.

In the fall, Margo Bates fills as many as 30 bags a week with fallen leaves from the towering oak trees in her yard in Baltimore’s Guilford neighborhood.

Acorns make the bags so heavy that she rakes those down onto the street first, so that passing cars will run them over, before bagging their crushed remains.

Otherwise, she said, “when the snow comes, and when you try to clean up your gardens to plant next year, you’re cleaning up wet leaves — yuck.”

Tens of thousands of people across the Baltimore region take part each year in the annual ritual of raking their leaves into heaping piles, bagging them and sending them away before family members arrive for Thanksgiving and snow covers the ground over the winter. While tradition and peer pressure from neighbors can make keeping a leaf-free yard feel like an obligation, raking them all away is actually bad for the yards, bees and other insects, and the rest of the environment, experts say.

“It’s good to leave as much leaf litter on the land as possible,” said Jon Traunfeld, director of the Home & Garden Information Center at the University of Maryland College of Agriculture and Natural Resources. “Leaves fall, and the nutrients from those leaves feed the plants.”

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A rainbow of foliage is reflected in the Loch Raven Reservoir. (Jerry Jackson / Baltimore Sun)

Environmentally friendly or not, the sight of a leafy yard along a street full of manicured lawns can earn the homeowner or renter “a hairy eyeball,” he said.

“Aesthetically, people don’t like it,” Traunfeld said. “People get really uptight about this. We really work hard at trying to change that mindset.”

Just like trees, plants and other vegetation, fallen leaves also absorb rainwater and reduce nutrient runoff, Traunfeld said, which is particularly important in Maryland for the health of the Chesapeake Bay.

“What you do on your property has downstream effects,” he said.

His advice? Turn the leaves into mulch by mowing over them with a lawnmower, and leave them on the yard or put them into compost piles. Then, instead of heading to the hardware store for mulch to line your gardens, spread a layer of the compost on the flowerbeds instead.

The process is known as “nutrient recycling,” Traunfeld said.

“By either letting the leaves decompose naturally or composting them yourself, you’re cutting out a step," he said. "The leaves can become the mulch. That way, we don’t have to go and buy fertilizer.”

Compost piles or bins are particularly handy if — like Bates — your yard is overwhelmed with so many leaves that merely mowing and leaving them would suffocate the grass. The 73 inches of rain Baltimore received last year and the current drought have been a “double whammy,” punishing the area’s lawns, Traunfeld said.

“With stressed lawns, you may want to err on the side of not leaving more than a half inch or an inch of chopped up leaves on top of the grass," Traunfeld said. “You want to be able to see grass. You don’t have to see all the grass, but you don’t want to see a solid, thick layer of mulched leaves."

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The Baltimore Running Festival (pictured) is just one of the fall footraces scheduled for the region. Other upcoming races include the Zombies Zoom 5K on the Gwynns Falls Trail, Charm City Run Oktoberfest 5 Miler and NCR Marathon and Half Marathon. (Algerina Perna / Baltimore Sun)

Leaving a layer of leaves on your yard also provides bees, which are being threatened by habitat loss, pesticides and climate change, a place to live over the winter, he said. And raking piles of them into the street can clog storm drains.

Most jurisdictions will collect leaves from residents, but re-using the debris at home “avoids the energy and fuel and cost and emissions involved with transporting these materials to a facility to manage them,” said Kaley Laleker, director of the Maryland Department of the Environment’s land and materials administration.

“Ideally, the best thing for residents to do is try to manage the materials onsite at their homes,” she said. “Recycling the leaves and other yard trimmings creates a product that can improve the soil."

If you do leave the leaf remnants out for your local jurisdiction to collect, Laleker said, be careful to keep out anything plastic or other non-compostable trash.

“Residents should check with their counties about what is accepted in their local programs,” she said.

To be sure, not everyone is a fan of leaving leaves be.

Bates slipped on wet leaves on the sidewalk in a recent year and tore her Achilles tendon, she said.

Bates has had to pull out miniature azaleas from her large garden, which also includes boxwoods, lime topiary, Hydrangea, myrtles, mums, Camellia, and Hosta, after wet leaves got stuck in the bushes and rotted them over the winter.

And mowing the garden isn’t exactly practical, she said.

“When you have the big trees, like we do in Guilford," the 25-year resident said, "you just have to bag them.”

The state overall is good at composting. An estimated 85% of yard trimmings in Maryland are recycled, mostly by the jurisdictions that collect them, Laleker said.

“Maryland residents as a whole are already very good at recycling yard trimmings,” she said. “Looking at ways to manage them onsite is the next step.”

If you have questions about gardening, yard maintenance or the environment in general, you can seek information and ask at the University of Maryland Extension’s Home & Garden Information Center website at extension.umd.edu/hgic.

“Any kind of questions — garden, landscape, lawn, insect — we answer it,” Traunfeld said.

Editor’s note: This article was originally published on Oct. 10, 2019.